This invention relates to an improvement of a tape recorder with a motor drive assisting mechanism.
Recently tape recorders with a so-called motor drive assisting mechanism have been developed in which a head slider, as a head position control member, can be moved to a predetermined position by means of an exclusive assisting motor.
These tape recorders may employ so-called soft-touch operation and may be combined with an auto-reverse mechanism or other mechanism.
Tape recorders of this type must be designed so that the sliding of the head is securely controlled in various operation modes and so that the heads are accurately located in positions corresponding to the operation modes.
However, conventional motor drive assisting mechanisms cannot always fully satisfy these requirements, and are subject to various drawbacks. For example, the head position controlled by the head slider cannot be readily detected or adjusted. Therefore, cue and review operations, in particular, may not be performed smoothly and accurately.
It is to be understood that setting the head position includes establishment of the operation modes and shifting the tape recorder from an operating mode to a stop mode. In setting the head position for the stop mode, however, it is necessary that the head slider be ready to be returned smoothly and securely. To counter voltage drop, it is also necessary to prevent reduction of the effective torque margin of the assisting motor.
A forward-reverse selector for changing the tape feeding direction is used for the motor drive assisting mechanism for the auto-reverse mechanism. As shown in FIG. 1, the forward/reverse selector is generally provided with left and right plungers 11 and 12 for forward/reverse shift control. Left and right playback sliders 14 and 15 are supported on a main chassis 13 so as to be slidable in the direction of arrows A and B. One end portions of left and right transmission levers 16 and 17 engage those of the left and right playback sliders 14 and 15, respectively. The transmission levers 16 and 17 are rockably mounted at the middle portion thereof on the main chassis 13. The other end portions of the transmission levers 16 and 17 are supported by core portions 111 and 121 of the left and right plungers 11 and 12, respectively.
If the right plunger 12 is energized, for example, its core portion 121 is attracted so that the right transmission lever 17 is rocked in the clockwise direction of FIG. 1. At this time, the right playback slider 15 engaging the one end portion of the right transmission lever 17 slides in the direction of arrow A against the urging force of a return spring 18. As the right playback slider 15 slides in this manner, the head slider 19 also slides in the direction of arrow A against the urging force of a return spring 20. Thereupon, a recording/playback head 21 mounted on the head slider 19 abuts against a tape surface, and a right pinch lever 22 is rocked together with the motion of the right playback slider 15. Thus, a right pinch roller 23 presses a tape against a capstan 24 for forward playback operation. If the left plunger 16 is energized, on the other hand, the left playback slider 14 is slid in the direction of arrow A by the left transmission layer 16. As the left playback slider 14 slides in this manner, the head slider 19 also slides in the direction of arrow A. Thereupon, the recording/playback head 21 abuts against the tape depending on the tape feeding direction. Thus, a left pinch roller 26 on a left pinch lever 25 presses the tape against a capstan 27 for reverse playback operation.
Constructed in this manner, the forward/reverse selector used in the motor drive assisting mechanism for the auto-reverse mechanism is expensive, due to the use of the two plungers, and requires a high capacity power source. Therefore, this forward/reverse selector is unsuitable for a small, portable tape recorder, and its additional power consumption increases the operating cost of the apparatus.
Moreover, some of the forward/reverse selectors used in tape recorders are normally associated with a head shift mechanism. As these forward/reverse selectors change the tape feeding direction, the head shift mechanism is actuated to shift a recording/playback head and other head(s) in accordance with the tape feeding direction.
Associated with the head shift mechanism, however, these conventional forward/reverse selectors are complicated in construction and expensive to manufacture.